Submitted to: Arkansas Agricultural Experiment Station Special Reports
Publication Type: Experiment Station
Publication Acceptance Date: 8/1/2000
Publication Date: N/A
Interpretive Summary: Although the USDA-ARS rice germplasm collection is very diverse there are "gaps" in the collection. Data show that only 10 countries constitute 81% of the collection. Currently, germplasm is being introduced into the US from Bangladesh, Brazil, China, Colombia, Egypt, Hungary, India, Ivory Coast, Japan, Korea, Myanmar, Nepal, Philippines, Russia and Taiwan. Germplasm from these countries has demonstrated apparent allelopathy to weed species, disease resistance, earliness, herbicide tolerance, high yield potential and superior grain quality. This germplasm can be used by scientists in variety development programs.
Technical Abstract: The USDA-ARS rice germplasm working collection contains 17,279 accessions from 110 countries or regions. The Dale Bumpers National Rice Research Center (DB NRRC) at Stuttgart, AR coordinates the systematic evaluation of the U.S. rice germplasm collection. Data for more than 30 different descriptors have been collected and are part of the germplasm resources information network (GRIN). Some of the descriptors include allelopathy amylose content, days from emergence to flowering, disease resistance, grain type, herbicide tolerance, kernel length, kernel weight, lodging, plant height, salt tolerance, yield etc. A broad range of genetic variability is present in GRIN for each descriptor. For example, amylose content ranges from 0.0 to 53.0%, days from emergence to flowering (37 to 219 days), kernel length (3.0 to 9.9 mm), kernel length/width ratio (1.0 to 8.0) plant height (41-208 cm), protein content (1.7 to 13.6%), salt tolerance (0.0 to 5.6), straighthead rating (1 to 9) and 1,000 kernel weight (6.9 to 46.0 g). Some accessions are tolerant to non-selective herbicides such as glyphosate and sulfosate, other accessions significantly increase crayfish production while other accessions apparently are allelopathic to weed species such as ducksalad (Heteranthera limosa) and barnyardgrass (Echinochloa crus-galli). HPLC chromatograms show significant differences in 5 different substances (peaks) when allelopathic accessions (i.e. PI 312777) are compared to accessions that demonstrate little or no allelopathic activity (i.e. Rexmont). Although the USDA-ARS rice germplasm collection is very diverse there are 'gaps' in the collection. For example, only 10 countries constitute 81% of the collection.